Rohon-beard neurons do not succumb to programmed cell death during zebrafish development.

Area of Science:

• Neuroscience
• Developmental Biology
• Cell Biology

Background:

• Neural development involves circuit refinement through cell death and synaptic pruning.
• Rohon-Beard neurons (RBNs) are the earliest mechanosensory neurons, crucial for rudimentary motor circuits.
• RBNs were previously thought to undergo significant cell death as dorsal root ganglion (DRG) neurons develop.

Purpose of the Study:

• To investigate the fate of neurogenin1-positive (ngn1+) RBNs during early zebrafish development.
• To challenge the established understanding of RBN programmed cell death.
• To explore the persistence and potential functional changes of RBNs.

Main Methods:

• Utilized zebrafish as a model organism.
• Employed genetic labeling (neurogenin1-positive) to track RBNs.
• Observed RBNs from early development up to 15 days post fertilization (dpf).

Main Results:

• Contrary to previous studies, ngn1+ RBNs do not undergo widespread programmed cell death.
• RBNs persist in zebrafish until at least 15 dpf.
• Observed medialization and shrinkage of RBN somas starting at 2 dpf, with gradual ngn1 downregulation.

Conclusions:

• The widespread programmed cell death of RBNs is not a fundamental aspect of early zebrafish neural development.
• ngn1+ RBNs persist and undergo significant morphological and molecular changes.
• This finding necessitates a re-evaluation of RBN function, persistence, and circuit refinement mechanisms.